/Engine/Source/Developer/TextureFormat/Public/Interfaces/ITextureFormat.h
InNumMips The total mips that the texture contains. InExtendedData If the texture is being built for a platform that provides extended data, pass it here. For platforms that don't need it (i.e. PC), this should be nullptr. InEngineParameters Holds a vairety of engine configuration constants, create with GenerateEngineParameters()
static int32 GetNumStreamingMipsDirect ( int32 InNumMips, bool bInCubeMap, bool bInVolumeTexture, bool bInTextureArray, const [FEncodedTextureExtendedData](API\Developer\TextureFormat\Interfaces\FEncodedTextureExtendedData) * InExtendedData, const [FTextureEngineParameters](API\Developer\TextureFormat\Interfaces\FTextureEngineParameters) & InEngineParameters )